// SPDX-License-Identifier: GPL-2.0-only

/*
 *  linux/drivers/cpufreq/cpufreq_userspace.c
 *
 *  Copyright (C)  2001 Russell King
 *            (C)  2002 - 2004 Dominik Brodowski <linux@brodo.de>
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/cpufreq.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/slab.h>

static DEFINE_PER_CPU(unsigned int, cpu_is_managed);
static DEFINE_MUTEX(userspace_mutex);

/**
 * cpufreq_set - set the CPU frequency
 * @policy: pointer to policy struct where freq is being set
 * @freq: target frequency in kHz
 *
 * Sets the CPU frequency to freq.
 */
static int cpufreq_set(struct cpufreq_policy *policy, unsigned int freq)
{
    int ret = -EINVAL;
    unsigned int *setspeed = policy->governor_data;

    pr_debug("cpufreq_set for cpu %u, freq %u kHz\n", policy->cpu, freq);

    mutex_lock(&userspace_mutex);
    if (!per_cpu(cpu_is_managed, policy->cpu)) {
        goto err;
    }

    *setspeed = freq;

    ret = __cpufreq_driver_target(policy, freq, CPUFREQ_RELATION_L);
err:
    mutex_unlock(&userspace_mutex);
    return ret;
}

static ssize_t show_speed(struct cpufreq_policy *policy, char *buf)
{
    return sprintf(buf, "%u\n", policy->cur);
}

static int cpufreq_userspace_policy_init(struct cpufreq_policy *policy)
{
    unsigned int *setspeed;

    setspeed = kzalloc(sizeof(*setspeed), GFP_KERNEL);
    if (!setspeed) {
        return -ENOMEM;
    }

    policy->governor_data = setspeed;
    return 0;
}

static void cpufreq_userspace_policy_exit(struct cpufreq_policy *policy)
{
    mutex_lock(&userspace_mutex);
    kfree(policy->governor_data);
    policy->governor_data = NULL;
    mutex_unlock(&userspace_mutex);
}

static int cpufreq_userspace_policy_start(struct cpufreq_policy *policy)
{
    unsigned int *setspeed = policy->governor_data;

    BUG_ON(!policy->cur);
    pr_debug("started managing cpu %u\n", policy->cpu);

    mutex_lock(&userspace_mutex);
    per_cpu(cpu_is_managed, policy->cpu) = 1;
    if (!*setspeed) {
        *setspeed = policy->cur;
    }
    mutex_unlock(&userspace_mutex);
    return 0;
}

static void cpufreq_userspace_policy_stop(struct cpufreq_policy *policy)
{
    pr_debug("managing cpu %u stopped\n", policy->cpu);

    mutex_lock(&userspace_mutex);
    per_cpu(cpu_is_managed, policy->cpu) = 0;
    mutex_unlock(&userspace_mutex);
}

static void cpufreq_userspace_policy_limits(struct cpufreq_policy *policy)
{
    unsigned int *setspeed = policy->governor_data;

    mutex_lock(&userspace_mutex);

    pr_debug("limit event for cpu %u: %u - %u kHz, currently %u kHz, last set to %u kHz\n", policy->cpu, policy->min,
             policy->max, policy->cur, *setspeed);

    if (policy->max < *setspeed) {
        __cpufreq_driver_target(policy, policy->max, CPUFREQ_RELATION_H);
    } else if (policy->min > *setspeed) {
        __cpufreq_driver_target(policy, policy->min, CPUFREQ_RELATION_L);
    } else {
        __cpufreq_driver_target(policy, *setspeed, CPUFREQ_RELATION_L);
    }

    mutex_unlock(&userspace_mutex);
}

static struct cpufreq_governor cpufreq_gov_userspace = {
    .name = "userspace",
    .init = cpufreq_userspace_policy_init,
    .exit = cpufreq_userspace_policy_exit,
    .start = cpufreq_userspace_policy_start,
    .stop = cpufreq_userspace_policy_stop,
    .limits = cpufreq_userspace_policy_limits,
    .store_setspeed = cpufreq_set,
    .show_setspeed = show_speed,
    .owner = THIS_MODULE,
};

MODULE_AUTHOR("Dominik Brodowski <linux@brodo.de>, "
              "Russell King <rmk@arm.linux.org.uk>");
MODULE_DESCRIPTION("CPUfreq policy governor 'userspace'");
MODULE_LICENSE("GPL");

#ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_USERSPACE
struct cpufreq_governor *cpufreq_default_governor(void)
{
    return &cpufreq_gov_userspace;
}
#endif

cpufreq_governor_init(cpufreq_gov_userspace);
cpufreq_governor_exit(cpufreq_gov_userspace);
